<p> </p>
<p>3D printing techniques have been applied in many fields to provide a potential for complex fabrication, and photopolymerization methods are the current possible path to fabricate nanoscale 3D structures. Multi-photon lithography is the most common tool to reach below 100-nm resolution. These methods require femtosecond lasers to reliably create sophisticated 3D polymeric nanostructures using nonlinear photopolymerization of a light-sensitive resin. Though these methods provide high accuracy and flexibility in advanced fabrication, they are essentially limited by their cost and throughput. Therefore, in this work, multiple approaches were examined to develop new methods for one-photon nonlinear 3D printing. </p>
<p>By controlling multiple competing processes in the radical polymerization scheme, a nonlinear photopolymerization effect is achieved using a one-photon absorption process with the assistance of inhibition radicals and controlled diffusion. This work makes use of this nonlinear response to fabricate 2D/3D structures using a continuous-wave diode laser, demonstrating a significantly more cost-efficient source for 3D nanolithography. In addition, a numerical model was constructed with the highly nonlinear response by actively controlling the consumption of the initiators with the assistance of these inhibitors, and it shows the same trend of nonlinearity from experiments. We use this model to study this dosage-based nonlinear response driven by the laser intensity in several 1D and 2D scenarios with different inputs and predicted the polymerization results in a confined voxel in the resin to support the observations from the experiments. Besides the demonstration of current one-photon nonlinear 3D printing, this work also involves some results of nonlinear response by operating local oxygen concentration and a two-step absorption nonlinear photoinitiator. These results help us to further study the potential of increasing the throughput of the one-photon nonlinear 3D printing process. </p>
<p>In conclusion, a new one-photon-based dose nonlinear process is introduced in this dissertation to achieve nanoscale 3D printing with a low-cost-405-nm diode laser operating at milliwatt level. By controlling the activation and transport of initiating and inhibiting radicals, we achieve patterning of the nanoscale features at a high scanning speed.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/20399274 |
| Date | 28 July 2024 |
| Creators | Shih-hsin Hsu (13171584) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/One-photon_3D_Nanolithography_using_Controlled_Initiator_Depletion/20399274 |
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